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为了研究辽宁省海城7.3级地震发生的地质背景——辽南地区的地壳构造,根据已有的反映深部界面起伏的重力资料,以及本文提出的方法除去新生代沉积和浅部构造影响后的重力异常,用等效压缩质面方法计算莫霍界面深度。并采用密度差异的原理,从重力异常中分解出康拉界面的影响,从而求得康拉界面的深度。根据13条计算剖面的结果,给出辽南地区的康拉界面和莫霍界面的分布。根据莫霍界面的起伏,此地区大致可划分为三个部分。中部:为一北东向的上地幔隆起带,北低南高,一直向西南延伸入渤海。隆起的东南坡陡,西北坡缓,且呈台阶式次第下倾。在此大的构造背景上展布了一系列具有相当规模的次一级正、负构造。地壳厚度在隆起部分为31—32公里,但其东缘较薄,约为30公里左右。东南部:地壳厚度一般为34—35公里,最大可达38公里.西北部:地壳厚度向西北方向由34公里逐渐增至40公里左右。海城地震就发生在中部隆起带的较陡的东南坡上。 文中对有关的计算方法作了简要的介绍。并对一些问题进行了讨论。
In order to study the geological background of the magnitude 7.3 Haicheng earthquake in Liaoning Province, the crustal structure in southern Liaoning Province, and based on the existing gravity data reflecting the undulation of the deep interface and the method proposed in this paper, the removal of Cenozoic sediments and shallow structures Gravity anomaly, calculate the Moho interfacial depth by the equivalent compressive mass plane method. Based on the principle of density difference, the influence of the interface of the Conra is decomposed from the gravity anomaly to get the depth of the interface of the Conra. According to the results of 13 calculated sections, the distributions of the Conra interface and the Moho interface in southern Liaoning are given. According to the ups and downs of the Moho interface, the area can be roughly divided into three parts. Middle: a northerly uplifted upper mantle uplift with north-south high and extending southwestward into the Bohai Sea. The uplifted southeast slope is steep and gentle on the northwestern slope, and is stepped downwards. On this large tectonic setting, a series of positive and negative constructions with a fairly large scale are distributed. The thickness of the crust is 31-32 kilometers in the uplift, but its eastern margin is thin, about 30 kilometers. Southeastern: crustal thickness is generally 34-35 km, up to 38 km.West: the thickness of the crust to the northwest from 34 km gradually increased to 40 km. The Haicheng earthquake occurred on the steeper southeast slope of the central uplift. The article gives a brief introduction about the calculation method. And some issues were discussed.